Rotary pump



D, A. FULTON 2,198,382

ROTARY PUMP Filed March :50, 1937 hgj $37 INVENJOR. fiana/o H r f ATTORNEY.

Patented Apr. 23, 1940 PATENT OFFICE ROTARY PUMP Donald A. Fulton,

Application March 30,

6 Claims.

This invention relates to rotary pumps for either liquid or gaseous fluids and particularly for compressing a gaseous or mixed gaseous and liquid refrigerant. l

Objects of this invention are to present a rotary pump having a positive displacement, a minimum number of moving parts, producing a uniform rate of flow, and one that will be efficient, dependable and long lived in continuous operation. Other obiects'and features of the invention will be evident hereinafter.

Fig. 1 is a longitudinal cross-section of the rotary pump. Fig. 2 is a partial longitudinal sectional view of the rotary pump taken at lines 22 of Fig. 1. Fig. 3 is an open end View of the pump taken at line 3-3 of Fig. 1. Fig. 4 is a partial longitudinal section of an optional construction of that portion of the rotary pump shown in section in Fig. 1..

Referring to Fig. 1, the pump comprises an enclosure or case l containing a cylindrical rotor H. The rotor makes a substantially fluid-tight fit with the inside cylindrical surface of the enclosure and is rotatably mounted on a main shaft 5 l3 journaled in the bearing l4. An.auxiliary shaft l5 extends axially from the main shaft through the rotary seal 55 and out through the end flange l8. A pulley keyed to the end of the shaft l5 serves to rotate the rotor II at any desired rate.

The-end surface of the rotor l l opposite the shaft l3 approximates an oblique cone in form, the point of which is coincident at 26 with the rotor axis 21. The base of the cone-shaped suri face is outlined by an approximately elliptical line 28 which is generated by the intersection of the said oblique conical and cylindrical rotor surfaces.

The shape and attitude of the conical surface 25 with respect to the axis of the cylindrical rotor is such that all imaginary plane surfaces intersecting one another on the line formed by the axis 21 form in turn by their intersection with the conical surface, straight convergent lines which intersect at equal angles at the point 26. Upon rotation of the rotor II the sides of the conical surface due to the obliquity of the cone axis with respect to the rotor axis function in the manner of a cam as described hereinafter.

The end of the enclosure or case adjacent the before-mentioned conical or cam-shaped rotor end surface 25, comprises a flange 29 carrying a cylindrical projection 30. A narrow diametral slot 3| extends longitudinally through the cylindrical end projection 30' and forms at the inner Santa Monica, Calif.

1937, Serial No. 133,864

portion thereof a circular recess 32 containing a segmental disc-shaped plate 33 and at the outer end a rectangular-shaped recess 34 containing a bearing plate 35. The inner end 36 of the bearing plate is circular in shape and closes and completes the outer portion of the circular recess 32. The said bearing plate is urged against the edge of the disc 33 by means of the leaf spring 31 which is in turn held under compression in its-recess 38 by means of the threaded disc 33.

The disc 33 as stated herebefore is a circular sector bounded by radial edges 40 and M intersecting at the point 26 at an angle equal to the v before-described angle subtended by the cone surfaces. The edges lll and 4! thus lie in contact throughout theirlengths with the cam-shaped end surface of the rotor H and are held in substantially fluid-tight contact therewith by the pressure of the said spring 3! acting through plate 35.

The end portion of the container Ill adjacent the flanged portion 29-3li carries circular recesses 42 and 43 which form a continuation of the inner portion of the circular recess 32 containing the disc 33. The disc 33 is thus free to rotate or rock in an oscillatory manner as indicated by arrows 44 about the point'26 as a center in the said circular recess and it is forced to do so upon the rotation of the rotor H by the cam action of the before-described rotor end surface. Thus upon rotation of the rotor the disc 33 is forced to rotationally oscillate about the point 26 as a center through an angle A which is equal to 180 minus the angle '13 subtended by the cone surface at the peak. The edge 40 of the disc thus moves to the position 40 and the edge 4! moves to the position 4| 1 as illustrated in dotted lines and return for each rotation of the rotor H during which time the said radial edges 40 and 4| of the disc 33 always remain in contact with the moving cam-like cone surface. The disc 33 thus divides the pump chamber between the rotor cam end and the flange surface 45 into two closed fluid-tight chambers of variable volume.

During the rotation of the rotor II the high portion of the cam surface illustrated by a radial line 46 in Fig. 3 and at line 40 in Fig. 1, moves in substantially fluid-tight contact around the inside face 45 of the flange 23.

Two ports. and 48 equidistant on either side of the before-described contact line 46 and spaced a distance from inside edge to inside edge approximately equal to the thickness of the disc 33 constitutes the inlet and outlet respectively 55 to the said two chambers formed between the cam-shaped rotor end 25 and the end flange 29 by ,he segmental dividing disc 33. The outlet p0 t 41 makes connection through duct with an annular distributor groove 5! cut around the midsection of the rotor. An outlet passage 52 makes connection between the groove 5| and the outlet pipe 53.

The inlet or suction of the rotary pump makes connection with the before-mentioned pump chamber formed between the. cam-shaped rotor end and the inside flange face 45 by way of pipe 55 and passage 56 into the annular groove 51 inside of the pump case and thence through the duct 58 and inlet port 48 into the said pump chamber.

The rotor ll carries two spaced rings GI and 62 which lie in suitable annular grooves on either side of the outlet passage groove 5|. These rings serve to maintain a substantially fluid-tight seal along the rotor surface between the inlet and outlet passages and between the pump chamber and the outlet passage respectively.

The rotary seal contained in the space unde the flange l8 and which serves to prevent leakage of fluid either into or out of the rotary. pump around the driving shaft l5 comprisesa metal thimble 62 having a tapered section 63 into which a pliable rubber ring [6 is thrust by a spring 64 acting under compression. The rubber ring l6 by its deformation under the pressure of the said spring 64- efl'ects a fluid-tight seal between the shaft l5 and the thimble 62 and they rotate together.. The thimble makes in turn a fluidtight slidingv or rotary contact with the stationary annular metallic ring 66 set into a recess in the inside of flange I8. Oil is supplied to the space 65 through an oil duct 61 to provide proper lubrication for the sliding surfaces of the sealing mechanism and the bearing 14.

Ordinarily when pumping a gaseous fluid such as in a refrigeration system, the lubricant is mixed in liquid form and circulates constantly with the.\ refrigerant. A trap formed by the offset between the inlet ducts 68 and 56 serves to catch and separate the lubricant from the gaseous stream and to allow it to flow through the duct 61 to the rotary'seal mechanism and to the bearing surfaces.

The rotary pump is adapted to besuccessfully operated by rotation in either direction. It may be preferable, however, when handling fluids under super atmospheric pressure to operate the pump so that the pipe 55 constitutesthe inlet or suction to the pump whereby the sealing mechanism in space 65 isat a minimum pressure. For purposes of illustration, therefore, the rotation of the pump rotor is assumed to be clockwise'as seen from line 33 in Fig. 1 and as shown in Fig 3 under which condition the pipe 55 will constitute the inlet to the pump and the pipe 53 the outlet. i

The. operation of the apparatus is as follows: Assuming clockwise rotation of the rotor II, as viewed in Fig. 3, the port 41 will move with the rotor in aclockwise direction as indicated by v the. arrow 43 from .the position shown towards the upper'portion of the segmental disc 33 which forms 'a fluid-tight seal with the cam-shaped rotor end surface along'the edge 4|. The beforedescribed high point of the cam-shaped rotor end which make a 'moving fluid-tight contact with the inside face 45 of the end flange 29, also moves with the said rotation of the rotor toward the segmental disc 33. Thus, as the rotor moves clockwise from the position shown to a position from that shown, the chamber formed between the cam-shaped end of the rotor and the inside face 450i the flange 29 and bounded at the ends by the leading edge of the sliding contact line 46 and the movable disc 33 at 4| will contract expelling fluid therefrom out through the port 41, duct 50, groove 5!, duct 52, pipe 53, and check valve 54.

At the same time immediately following the passage of the port 48 under the lower contact edge 40 of the disc 33, with the said rotation, of the rotor, the chamber formed between the end of the rotor and the inside face 45 of the flange and bounded by the trailing edge of the line of contact 46 and the lower portion of the segmental disc '33 will expand during the same following 180 of rotation drawing fluid into it through inlet pipe 55, duct 56, distributor groove 51, duct '58, and port 48.

The. hereinbefore-described pumping cycle is repeated for each 180 of rotation of the rotor ll resulting in two suction and two pressure impulses per revolution of the rotor. These impulses combine to form a substantially constant flow of fluid through the pump.

The displacement of the pump is a function of the diameter of the rotor and the angle A of the cam surface. The cam angle A may be'varied and the rotor diameter modified to obtain any desired displacement.

- Fig.4 illustrates an optional method of maintaining the edges of the disc 33 in fluid-tight contact with the rotor end surface. In this arrangement, the disc is divided into two sectors 10 and II each of which is forced against the end surface .of the rotor by the .U-shaped spring Ii which is retained in position by suitable slots I3 and 14 which receive the spring ends. When the two segments are thus employed the rotor end surface instead of forming a point as at 26 in Fig lis provided with a spherical sector 15 which makes a fluid-tight contact with corresponding spherical segmental surfaces at the inner end: of the circular segments I0 and H. The circular segments 10 and II can thus rotate through ar appreciable angle with respect to one anothei about the center 15 within the circular recess 31 without losing fluid-tight contact with the adjacent working surfaces.

The center of the inside face 45 of the flange-2! also contains recesses-forming portions of a spherical segment there on either side of the $101 32 which completes the spherical socket int( which the spherical portion 15 fits and forms 2 fluid tight seal during rotation.

illustrated in said Figs. '1-3 are desirable t4 provide for compensation for wear between thl moving pump and cam surfaces and to main tain them in fluid-tight contact, but these ele ments may be omitted and'the flange 29 ant cylindrical portion 36 constructed of a solid piec with only an accurately machined circular reces provided therein to carry the disc 33, withou detrimental results to the operation of the ap paratus of the invention.

The apparatus of this invention probably find its most important application in the compressiol and circulation of volatile liquid refrigerants in connection with the compressionsystem of reerants.

The apparatus of this invention, however, is

not limited to refrigeration systems but is applicable and advantageous for pumping any fluid, gaseous or liquid, or a mixture of gaseous and liquid fluids.

This invention, therefore, is not to -be' restricted by the preferred embodiment illustrated herein but is to be limited only by the scope of the following claims.

I claim as my invention:

1. A rotary pump comprising a casing, a rotor in said casing having a cam-shaped end surface, a pair of movable plates having the shapes of circular sectors each bearing along one radial edge upon said cam-shaped surface, means to support said movable plates whereby they are free to rotate within limits, and means between said plates to urge them into contact along said radial edges with said cam-shaped surface, whereby the said radial edges thereof can follow said cam-shaped surface upon rotation of said rotor, said plates together with said cam-shaped surface and walls of said casing defining a chamber of variable volume, means to admit and discharge fiuid from said chamber and means to ume, means to admit and discharge fluid from said chamber and means to rotate said rotor within said casing.

4. A rotary pump comprising a casing, a rotor in said casing having an oblique cone-shaped end cam surface, said cone-shaped cam surface forming equal angles on all planes intersecting each other along the rotor axis, a movable plate bearing upon said cam surface and together with saidcam surface and walls of said casing defining a chamber. of variable volume, said plate forming 'amajor circular sector subtending between its radial edges an angle equal to the apex angle of said cam surface, means to admit and discharge fluid from said chamber, and means to rotate said rotor within said casing.

5. A rotary pump comprising a casing, a rotor in said casing having a cam-shaped end surface, a movable partition bearing upon said camshaped surface, said partition having the form of a major circular sector and defining with said cam-shaped end surface and with walls of said casing a chamber of variable volume, means to admit and discharge fluid from said chamber and means to rotate sa'idrotor within said casing.

6. A rotary pump comprising a casing having an end wall, a rotor in said casing with ,its axis of rotation'normal to said casing end wall and having an oblique cone-shaped end cam surface, the shape and attitude of said conical surface with respect to the axis of said rotor being such that all imaginary plane surfaces intersecting one another on said axis form by their intersection with said conical surface, straight convergent lines which intersect at equal angles at the apex of said cone, a portion of said cam surface making a moving fluid-tight contact with said 'end wall at all times, a movable plate bearing at its edge upon said cam surface and together with said cam surface and Walls of said casing defining a chamber of variable volume, means to admit and discharge fluid from said chamber and. means to rotate said rotor within said casing.

- DONALD A. FULTON. 

